Improving safety and sustainability of urban transport surfaces through the recycling of reclaimed extinguishing powders

Abstract

Fire resistance of transport surfaces is a crucial aspect, especially in specific contexts such as road and railway tunnels in urban areas. In fact, tunnels are characterized by specific environmental and logistic conditions that make the consequences of a fire event severer. Furthermore, as far as bituminous mixes are concerned (flexible pavements, blankets for railways and rapid transit systems), the fire resistance of bituminous materials can have an outstanding role in terms of safety and security. Indeed, these materials burn at medium temperature (400- 500°C) and release toxic smokes. This fire behavior makes bituminous pavements unsuitable for tunnel contexts. To this end, many studies tried to demonstrate that, by adding virgin flame-retardant additives, it is possible to improve the performance of bituminous pavements, in terms of mechanical properties and fire resistance. On the other hand, owing to the fact that a sustainable transportation surface needs to comply with environmental issues, meeting the needs of present-day users without compromising those of future generations, the use of recycled materials is becoming more and more relevant. In the light of the above premises, the objective of this study is to evaluate the effects of Reclaimed Extinguisher Powders (REP) on the performance of bituminous mixtures in urban transport surfaces. Fire resistance, mechanistic properties and environmental compatibility were considered. An experimental plan was designed and carried out. Results showed that the addition of REP can improve the fire resistance of asphalt binders and bituminous mixtures, without compromising mechanistic and environmental performance. Practical applications and perspectives in rehabilitation, maintenance, and research are outlined. Recommendations for future studies involving the application and implementation of the proposed concepts and solutions to a wider spectrum of materials and urban transport systems conclude the study. Outcomes are expected to benefit both practitioners and researchers. © 2012 WIT Press.